Microarray technology has broad applications in cancer research such as identification of cancer markers and gene expression profiling for diagnosis, treatment, and prognosis. Maintenance of a Core DNA Microarray Facility in a comprehensive cancer research center is critical for the success of a growing number of investigators with peer-reviewed funding. The Microarray Facility was established in 1999 using institutional and developmental funds from the CCSG. The Facility provides both printed cDNA and oligo arrays, for investigators to perform gene expression analysis, and full microarray services from RNA sample labeling to array scanning, for those investigators who do not have the capacity to perform microarray experiments in their own laboratories. The Facility also helps investigators to design and print custom microarrays to meet their specific research goals. The Facility is used by 20 investigators, all with peer-reviewed funding, from 9 research Programs in all three Divisions of Fox Chase Cancer Center (FCCC). The microarray usage has increased more than 200% from the year 2002 to 2003 and reached 1,300 microarrays per year. With an increasing number of research grants involving microarray analysis awarded recently, and the establishment of a Laser Capture Microdissection Facility at the Center, combined with RNA amplification procedure which enables small clinical cancer samples to be applied to microarray analysis, we anticipate a 100%-200% increase over the next five years. The microarray products of the Facility include human 40k cDNA and 30k oligo arrays, mouse 15k cDNA and 32k oligo arrays, and 6k yeast oligo arrays. A rat oligo library will be acquired to meet the needs of those investigators using rat models to study breast and ovarian oncogenesis. The Facility has also designed and produced customer design specific arrays, such as DNA repair process-related gene arrays. Standard microarray procedures and optimized labeling and hybridization kits, as well as a Microarray Training Program, have been made available to microarray users. A comprehensive microarray quality control procedure has been implemented to ensure the quality of microarray products and services. The Facility coordinates with the Bioinformatics Facility for microarray data analysis and management.